Several Types of Bilayer Smectic Liquid Crystals with Ferroelectric and Antiferroelectric Properties in Binary Mixture of Dimeric Compounds

Abstract

The mesomorphic behavior and phase structure were examined in the mixture of two kinds of dimeric compounds, alpha,omega-bis(4-alkoxyanilinebenzylidene-4'-carbonyloxy)pentane (mOAM5AMOm), by optical microscopy, X-ray diffraction, polarization switching, and second-harmonic generation measurements. One compound is 4OAM5AMO4 with a short terminal alkyl chain that forms a single-layer smectic phase (SmCAs) with a random mixing of spacer and tail groups. Another compound is 16OAM5AMO16 with a long terminal alkyl chain that forms a chiral, anticlinic, and antiferroelectric bilayer phase (SmCAb) with the bent molecules tilted to the bilayer. By mixing these two compounds, the SmCAs phase of 4OAM5AMO4 is easily destabilized, leading to the wide content region of the bilayer phases. In the bilayer regime, three other smectic phases are newly induced. Two of them are antiferroelectric and ferroelectric phases in which the molecules lie perpendicularly with respect to the layer. The other shows no polar response to an external electric field and behaves like a smectic A. The new appearance of these bilayer phases is discussed as a mixing effect of long and short tail groups.

Double gyroid structures made of asymmetric dimers

“…It is known that such flexibility leads to special structures, for example twist bend nematics, [27][28][29][30] modulated smectics [31,32] and broken-layer type columnar phases. [33,34] There is also limited number of reports about cubic phases formed by symmetric dimeric molecules with long internal spacer. [35,36] …”

New nanocomposites based on polyamide containing imine groups reinforced with functionalized polyethyleneimine‐modified ZnO nanoparticles; fabrication, characterization and lead ion adsorption studies

“…Generally, polymers containing azo as a dye chromophores, imine and naphthalene rings have been noticed as kind of materials with unique optical properties . Polyazomethines have been exhibited interesting optical properties such as PL emission and adsorption of UV‐Vis due to their resonance stabilization in Schiff base structure . Because of the presence imine group (‐N=CH‐), polyazomethine have been introduced as isoelectronic materials .…”

Linear Free‐Energy Relationships Applied to the 13C NMR Chemical Shifts in 4‐Substituted N‐[1‐(Pyridine‐3‐ and ‐4‐yl)ethylidene]anilines

“…Azomethines have emerged in the past two decades as promising materials for applications in photonics and optoelectronics. Low molecular weight compounds and polymers with the C═N unit are investigated as bent‐core and rod‐shaped liquid crystals , and depending on the chemical structure, they exhibit one mesophase or rich polymorphism . The favorable properties of azomethines are mostly governed by extended π‐conjugated system, in which the C═N unit is contained, and are sensitive even to subtle changes in it.…”